Bone marrow transplantation requires large numbers of pluripotent hematopoietic stem cells to achieve a successful clinical outcome. Therefore, there is a pressing medical need for methods to expand stem cells ex vivo and accelerate their engraftment in vivo. These steps may be supported by cytokine-producing stromal cells. The scientists at Artecel Sciences have developed proprietary techniques to isolate and culture human stromal cells from adipose tissue that can be used for autologous and allogeneic transplantation. This SBIR investigates the hypotheses that adipose derived stromal cells will (1) support hematopoietic progenitor cell proliferation and differentiation in vitro and (2) accelerate their engraftment in vivo. Aim 1 (Phase I) will demonstrate that human adipose derived stromal cells will support proliferation of multipotent and pluripotent hematopoietic progenitors in short and long term cultures using flow cytometric and methylcellulose assays. This work provides a foundation for Phase H studies to determine: (Aim 3) The ability of ex vivo expanded hematopoietic progenitors to repopulate sublethally irradiated NOD/SCID mice; (Aim 4) The ability of adipose derived stromal cells to accelerate hematopoietic stem cell engraftment in sublethally irradiated NOD/SCID mice. PROPOSED COMMERCIAL APPLICATION: This SBIR will develop technology with application to all patients receiving bone marrow transplantation. Each year, 20,000+ patients under this therapy at an individual cost of $100,000. Artecel Sciences technology has the potential to significantly reduce the clinical and financial burden of these procedures.